A Comet Twice the Size of Rhode Island — the Biggest Ever Seen — Is Heading Towards Our Sun It's traveling at 22,000 miles an hour.
NASA's Hubble Space Telescope has calculated the size of a massive comet nucleus observed last year, and it's the largest ever spotted, measuring 80 miles across —about twice the width of Rhode Island — and weighing 500 trillion tons.
For comparison, most comets are just a few miles wide and would fit inside a small town, but the gigantic discovery, called Comet C/2014 UN271 (Bernardinelli-Bernstein), boasts a nucleus that's 50 times larger than those of most known comets and a mass that's 100,000 times greater than that of a typical comet found near the sun.
The former record holder, discovered in 2002 by the Lincoln Near-Earth Asteroid Research (LINEAR) project, had a nucleus estimated to be 60 miles across.
Despite being a standout for its size, C/2014 UN271 is likely one of many yet to be spotted. "This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system," says David Jewitt, a professor of planetary science and astronomy at the University of California, Los Angeles (UCLA). "We've always suspected this comet had to be big because it is so bright at such a large distance. Now we confirm it is."
The 4-billion-year-old comet was first spotted in November 2010 by astronomers Pedro Bernardinelli and Gary Bernstein in archival images from the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile. At that time, it was 3 billion miles from the sun, and though it's heading towards our sun at a rate of 22,000 miles an hour, researchers say it will never get closer than one billion miles away, a bit farther than the planet Saturn — and it won't get there until 2031.
The comet is believed to originate from the Oort Cloud, a hypothesized nesting ground of trillions of comets first theorized by Dutch astronomer Jan Oort in 1950, but the cloud's existence remains unconfirmed as the comets are too faint and distant to be observed directly.